1. Field of the Invention
The present invention relates to a realistic robot which is constructed as a result of modeling the operation and mechanism of a living body, and, more particularly, to a legged mobile robot in which the mechanism of the body of a legged mobile animal, such as a human being and a monkey, is modeled.
Even more particularly, the present invention relates to a legged mobile robot which can operate independently or semi-independently while being subjected to various external forces in the living space/living environment of human beings. Still more particularly, the present invention relates to a legged mobile robot which can operate while being subjected to an external force as a result of coming into contact with an obstacle or other external objects, and which makes it possible to reduce shock which is produced when it comes into contact with an external object.
2. Description of the Related Art
A robot is a mechanical device which moves by emulating the movement of a human being by making use of electrical and magnetic actions. The term robot is said to be derived from the Slavic word ROBOTA (slavish machine). In our country, the widespread use of robots began from the end of the 1960s, many of which were industrial robots, such as manipulators and conveyance robots, used, for example, for the purpose of achieving automatic production operations in factories without humans in attendance.
Stationary robots, such as arm robots, which are implanted at certain places carry out, for example, parts assembly/sorting operations only at fixed/local working spaces. In contrast, the working space of movable robots is not limited. The robots move along a predetermined path or a pathless place in order to perform predetermined or any human tasks in place of human beings or to provide a wide variety of other services in place of human beings, dogs, or other living beings. Of the movable robots, legged mobile robots, though being unstable compared to crawler and tire type robots so that their postures and walking are difficult to control, are excellent robots in that they can go up and down steps and ladders, go over obstacles, and flexibly walk/run on any surface, regardless of whether the surface is a leveled or an unleveled surface.
In recent years, progress has been made in the research and development of legged mobile robots, such as pet robots which emulate the movements and mechanisms of the body of animals, such as dogs and cats, which walk on four feet, and humanoid robots which are designed as a result of modeling the movements and mechanisms of the body of animals, such as human beings, which walk erect on two feet. Accordingly, there is a higher expectation of putting them into practical use.
The significance of carrying out research and development of one type of legged mobile robots called humanoid robots can be understood from, for example, the following two viewpoints.
The first viewpoint is related to human science. More specifically, through the process of making a robot having a structure which is similar to a structure having lower limbs and/or upper limbs of human beings, thinking up a method of controlling the same, and simulating the walking of a human being, the mechanism of the natural movement of a human being, such as walking, can be ergonomically understood. The results of such research can considerably contribute to the development of various other research fields which treat human movement mechanisms, such as ergonomics, rehabilitation engineering, and sports science.
The other viewpoint is related to the development of practical robots as partners of human beings which help them in life, that is, help them in various human activities in living environments and in various circumstances in everyday life. Functionally, in various aspects of the living environment of human beings, these robots need to be further developed by learning methods of adapting to environments and acting in accordance with human beings which have different personalities and characters while they are taught by human beings. Here, it is believed that making the form and structure of the robot the same as those of a human being is effective for smooth communication between human beings and robots.
For example, when teaching a robot a way of passing through a room while avoiding obstacles which should not be stepped on, it is much easier for the user (worker) to teach it to a robot walking on two feet which has the same form as the user than to a crawler-type or a four-footed robot having a completely different structure from the user. In this case, it must also be easier for the robot to learn it. (Refer to, for example, Controlling a Robot Which Walks On Two Feetxe2x80x9d by Takanishi (Jidosha Gijutsukai Kanto Shibu  less than Koso greater than  No. 25, April, 1996.)
Most of the working space and living space of human beings are formed in accordance with the behavioral mode and the body mechanism of a human being which walks erect on two feet. In other words, for moving present mechanical systems using wheels or other such driving devices as moving means, the living space of human beings has too many obstacles. It is preferable that the movable range of the robot be about the same as that of human beings in order for the mechanical system, that is, the robot to carry out various human tasks to help them or in place of them, and to deeply penetrate the living space of human beings. This is the reason why there is a great expectation of putting the legged mobile robot into practical use. In order to enhance the affinity of the robot to the living environment of human beings, it is essential for the robot to possess a human form.
Humanoid robots can be used to carry out various operations, such as in industrial activities/production work, in place of human beings. They carry out in place of human beings dangerous/difficult operations at places where human beings cannot enter easily. Examples of the dangerous/difficult operations include maintenance work at nuclear power plants, thermal power plants, or petrochemical plants, parts transportation/assembly operations in manufacturing plants, cleaning in tall buildings, and rescuing of people at, for example, places where there is a fire.
Another application of the humanoid robot is related to the living together in the same living space as human beings, that is, to entertainment. In this type of application, the robot is deeply characterized as being closely connected to life rather than as helping human beings in life by, for example, performing tasks in place of them.
For entertainment robots, the production of an operation pattern, itself, which is executed during the operation is a theme regarding the research and development thereof rather than the constructing of them so that they can be industrially used as specified with high speed and high precision. In other words, it is preferable that the whole body harmoniously moving type operation mechanism which animals, such as human beings and monkeys, which walk erect on two feet actually possess be faithfully reproduced in order to achieve smooth and natural movement. In addition, in emulating highly intelligent animals, such as human beings and monkeys, which stand in an upright posture, it is to be considered that the use of an operation pattern which uses the four limbs is natural as a living body, and it is desirable that the movements are sufficiently indicative of emotions and feelings.
Entertainment robots are required not only to faithfully execute a previously input operation pattern, but also to act in a lively manner in response to the words and actions of a person (such as speaking highly of someone, scolding someone, or hitting someone). In this sense, entertainment robots which emulate human beings are rightly called humanoid robots.
When humanoid robots which walk on two feet are formed to operate in a working space, they are constructed so as to possess many more degrees of freedom than other portable robots, such as crawler-type robots and robots which walk on four feet. Therefore, various portions of the surface of the robot come into contact with the external world, depending on the posture of the robot, such as standing upright on two feet while not moving, lying on its side, and sitting on a chair. In other words, there may be cases where the state of contact of the humanoid robot with the external world need to be determined in detail in various working circumstances. In addition, it is necessary to reduce shock which is produced when the robot loses its balance and falls down even though a controlling operation is carried out or when the robot comes into contact with an obstacle or other external objects.
Regarding robots in which sensors for measuring externally exerted contact pressures and shock are installed, various proposals have been made, and research and development has been conducted. However, a conventional on/off type contact sensor does not provide the precise contact pressure, so that, when, for example, the robot comes into contact with something soft, one cannot exactly know what portion of the robot has come into contact with the soft object. On the other hand, when the robot comes into contact with something hard, one cannot precisely know with what force the robot is in contact with the hard object from only a piece of information from the on/off type contact sensor.
A conventional independent contact pressure sensor only outputs information regarding the contact pressure, so that it cannot provide information regarding the area of contact of each portion of the body of the robot.
Sensor modules which are constructed so as to incorporate only the conventional contact pressure measuring function cannot reduce a strong shock which the robot receives when it falls down or collides with an external object. This affects the output from the sensor, and causes the controlling operation of the robot to become less stable.
When the sensor modules which are disposed so as to be distributed at corresponding portions of the whole body of the robot are fixedly mounted so that they cannot be removed, it becomes difficult to access the internal mechanisms of the sensor modules, thereby reducing maintainability of the robot.
Most of the sensor parts which are disposed so as to be distributed at the corresponding portions of the whole body of the robot are sensors of the type which electrically detect very weak signals. When a power supply for supplying electrical power to such sensors is also used for joint actuators and a controlling unit for controlling the actuation of the actuators, power supply noise which is produced when, for example, the operations start or stop may prevent the detection of accurate sensor information.
When the power supply which is used for the sensors is used for other electrical/electronic parts, it is necessary to use a circuit which includes parts, such as inductors and capacitors, for reducing noise. Therefore, the control device of the robot is increased in size, making it difficult to design it and increasing production costs.
In the first place, in order to sufficiently and effectively realize the functions of the sensors for detecting the state of the external world, the number of locations where the sensors are mounted is considerably limited (for example, for a legged mobile robot which includes four limbs, the mounting locations are the finger tips and the tips of the toes). Therefore, when an electrical power system is constructed by using a single power supply, the total lengths of the electrical power lines which are connected to the sensor modules become long, so that they are affected by noise more easily. In addition, in correspondence with the increased wiring lengths, the wiring design becomes complicated, and the complicated wiring design may restrict the structure of the whole robot.
For example, by forming the sensor modules into battery actuation type modules, and separating them from the power supply which is provided for the other electrical/electronic parts, the problem of noise will be overcome. However, since the forms of conventional cells which are generally used are limited, the robot is subjected to many limitations, so that, for example, the structure or shape, or the external design must be changed.
Hitherto, batteries/cells have been mainly cylindrical in shape. Therefore, when a battery pack comprising a plurality of batteries/cells are used, it becomes difficult to achieve a thin, light structure. Consequently, it inevitably becomes a thick structure, such as a rectangular parallelepiped structure. As a result, depending on where the battery pack is disposed, the whole robot loses its balance in terms of its weight, so that it may be difficult to carry out a posture control operation.
Accordingly, it is an object of the present invention to provide an excellent legged mobile robot which can operate while being subjected to various external forces in the living space/living environment of human beings.
It is another object of the present invention to provide an excellent legged mobile robot which can independently or semi-independently operate while being subjected to external forces as a result of coming into contact with an obstacle or other external objects, and which makes it possible to reduce shock which is produced when the robot comes into contact with an external object.
It is still another object of the present invention to provide an excellent legged mobile robot which includes sensors which are disposed so as to be distributed at corresponding portions of the robot in order to detect the state of the external world.
It is still another object of the present invention to provide an excellent legged mobile robot which makes it possible to suitably supply electrical power to the sensors which are disposed so as to be distributed at the corresponding portions of the robot in order to detect the state of the external world, and to obtain accurate sensor outputs without being affected by noise.
To these ends, according to a first aspect of the present invention, there is provided a legged mobile robot including at least lower limbs and a trunk. The robot comprises an external module which is provided at at least one portion of the robot so as to be removably mounted thereto, the external module/each external module including a sensor for measuring contact pressure.
The external module may be removably mounted to a head of the legged mobile robot.
The external module may be removably mounted to a front portion or a back portion of the trunk of the legged mobile robot, or the external modules may be removably mounted to the front portion and the back portion of the trunk of the legged mobile robot. The trunk of the legged mobile robot may be divided into a trunk front portion, a trunk back portion, a trunk left side portion, and a trunk right side portion in order to construct the external modules so as to be removable from these divided portions.
The external module may be removably mounted to a shoulder of the legged mobile robot.
The external module may be removably mounted to an outer portion or an inner portion of an upper arm of the legged mobile robot, or the external modules may be removably mounted to the outer portion and the inner portion of the upper arm of the legged mobile robot.
The external module may be removably mounted to an outer portion or an inner portion of a forearm of the legged mobile robot, or the external modules may be removably mounted to the outer portion and the inner portion of the forearm of the legged mobile robot.
The external module may be removably mounted to a front portion or a back portion of a thigh of the legged mobile robot, or the external modules may be removably mounted to the front portion and the back portion of the thigh of the legged mobile robot.
The external module may be removably mounted to a front portion or a back portion of a crus of the legged mobile robot, or the external modules may be removably mounted to the front portion and the back portion of the crus of the legged mobile robot.
The external module may be removably mounted to buttocks of the legged mobile robot.
The external modules may be removably mounted to left and right hands of the legged mobile robot.
The external module/each external module may comprise engaging means for engagement with a corresponding portion of the legged mobile robot.
The external module/each external module may comprise a base layer for preserving the shape of the module corresponding thereto, a sensor layer for detecting contact pressure which is externally applied, and a shock-absorbing layer for transmitting to the sensor layer corresponding thereto shock or contact pressure which is externally applied.
The sensor layer/each sensor layer may comprise a plurality of sensors which are disposed so as to be distributed on the base layer corresponding thereto.
The sensor layer/each sensor layer may comprise a sheet-shaped pressure sensor which is laid on the base layer corresponding thereto.
The external module/each external module may include a circuit layer comprising a printed wiring board having a predetermined wiring pattern thereon. The circuit layer/each circuit layer may have mounted thereto circuit components including an AD converter for converting a sensor output from the corresponding sensor layer to a corresponding digital signal and a microprocessor for processing the corresponding converted digital signal.
When the external module/each external module comprises a base layer, a sensor layer, and a shock-absorbing layer, the legged mobile robot may further comprise a contact determining section for controlling in a centralized manner information regarding the contact pressure which is externally supplied, based on the sensor output from the external module/each external module. The contact determining section is, for example, installed at a central control system (not shown) for executing a general controlling operation of the movement of the whole body of the legged mobile robot.
At present, the contact determining section is capable of controlling in a centralized manner what amount of contact pressure is being applied to what location of the robot, and of estimating, for example, the volume, the mass, the hardness, and the material of the object with which the robot is in contact as a result of analyzing the contact pressure data at each portion, so that the object itself can be specified.
According to a second aspect of the present invention, there is provided a legged mobile robot including at least lower limbs and a trunk. The robot comprises an actuating section for realizing movement of the lower limbs and/or the trunk, the actuating section being operable by electrical power, a computing/controlling section for controlling the operation of the actuating section, the computing/controlling section being operable by electrical power, a first power supply section for supplying electrical power to the actuating section and/or the computing/controlling section, and an external module which is provided at at least one portion of the robot so as to be removably mounted thereto, the external module/each external module including a second power supply section.
A sensor for measuring contact pressure or the like may be provided at at least one portion of the robot. In this case, by supplying electrical power to the sensor/each sensor from the corresponding second power supply, it is possible to eliminate the effects of noise which is produced at the first power supply section.
The external module/each external module may include engaging means for engagement with a corresponding portion of the legged mobile robot.
The external module/each external module may further include a base layer for preserving the shape of the corresponding module, an electrical power layer having the corresponding second power supply section installed therein, and a covering layer for externally covering the corresponding electrical power layer.
When the external module/each external module comprises a base layer, an electrical power layer, and a covering layer, the second power supply section/each second power supply section may be a removable battery pack, and the base layer/each base layer may include a terminal for electrical coupling with the corresponding battery pack.
The second power supply section/each second power supply section may be a removable battery pack. In this case, the base layer/each base layer may have a terminal for electrical coupling with the corresponding battery pack disposed thereon.
The second power supply section/each second power supply section may be a secondary battery which is chargeable and reusable. The battery is, for example, a lithium ion polymer secondary battery which uses gel polymer electrolyte.
According to a third aspect of the present invention, there is provided an external module for a robot which is removably mounted to the robot. The external module comprises a base layer for preserving the shape of the module, a sensor layer for detecting contact pressure which is externally applied, a shock-absorbing layer for transmitting to the sensor layer shock or contact pressure which is externally applied, and engaging means for engagement with an appropriate portion of the robot.
In a first form of the third aspect, the sensor layer comprises a plurality of sensors which are disposed so as to be distributed on the base layer.
In a second form of the third aspect, the sensor layer comprises a sheet-shaped pressure sensor which is laid on the base layer.
In a third form of the third aspect, the external module may include a circuit layer comprising a printed wiring board having a predetermined wiring pattern thereon. The circuit layer may have mounted thereto circuit components including an AD converter for converting a sensor output from the sensor layer to a digital signal and a microprocessor for processing the converted digital signal.
According to a fourth aspect of the present invention, there is provided an external module for a robot which is removably mounted to the robot. The external module comprises a base layer for preserving the shape of the module, an electrical power layer having a power supply section for supplying electrical power installed therein, a covering layer for externally covering the electrical power layer, and engaging means for engagement with an appropriate portion of the robot.
In a first form of the fourth aspect, the electrical power layer is a removable battery pack, and the base layer has a terminal for electrical coupling with the battery pack formed thereon.
In a second form of the fourth aspect, the electrical power layer comprises a secondary battery which is chargeable and reusable. The battery is, for example, a lithium ion polymer secondary battery which uses gel polymer electrolyte.
In the legged mobile robot of the first aspect of the present invention, in order to determine the state of contact of the robot with the external world, sensors which can measure contact pressure are disposed so as to be distributed at corresponding portions of the whole body of the robot. In addition, external modules which use shock-absorbing members for reducing shock are disposed at the corresponding portions of the whole body of the robot. The external module forms the structure of the third aspect of the present invention.
Each external module covers its corresponding portion of the robot, and acts as an external part for protecting the robot from external shock. The external module of the third aspect may be constructed so as to be removable from the body of the robot.
The external modules are given forms/structures which allow them to fit the upper limbs, the lower limbs, the front portion and the back portion of the trunk, the arms, etc. With this being included as part of the designing process, they can be united with the robot.
By using, for example, pressure sensors which can measure contact pressures in the external modules, the contact locations can be determined even when the robot comes into contact with a soft object. In addition, it is possible to determine the degree of contact (such as whether the robot is lightly or strongly in contact with an external object).
When a plurality of sensors which can measure contact pressure are disposed so that they are distributed throughout the whole body of the robot, pieces of information concerning the contact areas of portions of the corresponding external modules can be provided. By providing a shock-absorbing member near the measurement surface of each sensor, the range which each sensor can measure is increased by the pressure transmitting action of each shock-absorbing member. Therefore, it is possible to measure a wider range with a small number of sensors.
By using sheet-type pressure sensors, the contact pressures of various measurement points can be measured, so that pieces of information concerning the contact areas of portions of the corresponding external modules can be provided. By disposing a shock-absorbing member at the surface of each external module, it is possible to reduce shock which is produced when the robot falls down or comes into contact or collides with an obstacle or other external objects. Therefore, the output from each sensor and, thus, the controlling operation can be kept stable.
By constructing the sensors in modules which function as external parts, the devices installed inside the robot can be protected. In addition, by disposing each external module on the surface of its corresponding movable portion, such as a joint, interference between portions of the robot by its own movement (such as interference between the trunk and an arm) can be prevented from occurring.
By providing a shock-absorbing member on the surface of each external module, it is possible to protect each sensor from a large shock which is produced, for example, when the robot falls down or collides with an obstacle.
By constructing each external module which acts as a sensor so as to be removable from the body of the robot, the internal devices can be easily accessed, so that maintainability of the robot is enhanced.
According to the second and fourth aspects of the present invention, component parts other than the main power supply such as batteries, that is, small power supply modules are distributed in the empty space of the robot, so that space distribution is improved.
When batteries are provided in the external modules, they become relatively heavy. However, by constructing them so as to be removable from the body of the robot, and adjusting the location of the center of gravity of the robot depending on whether or not external modules are provided at their corresponding portions, the degree of balance in terms of its weight can be improved. As a result, the walking and other movements of the robot can be stabilized.
By mounting the battery-contained external modules near sensors and other functional parts which operate using electrical power, it is possible to supply electrical power to each location without using the main power supply of the robot. In this case, it is possible to reduce the length of each electrical power line connected to its corresponding functional part, so that the designing of the wiring which becomes a problem when reducing the size of the robot and achieving higher density in the robot can be greatly simplified.
In addition, by mounting the battery-contained external modules near sensors and other functional parts which operate using electrical power, the power supplies of the sensors and the other functional parts can be separated from the main power supply. As a result, the functional parts are freed from the influences of the noise which is generated when, for example, the actuation of the joint actuators is started or stopped.